external keyboard ports
There are two USB ports on the sides of the extended, wired, keyboard I use with my MacBook Pro when it's docked. What do they do? When I plug in a USB charging cable no power is supplied for charging.
Is this an Apple keyboard? There are several variants of the extended wired boards and they can have different ports. Find a magnifying glass, flip the board over and look for a Model number like A1843, A1048, A1243, etc. Please tell us what you find.
On those with USB ports on the sides, those ports are for attaching only low-power USB devices, specifically mice. They do not produce enough power to charge anything or work with a mass-storage device like and external drive or USB flash drive. Older Mac USB wired keyboards have no batteries; they get their power from the computers' USB port.
The current Apple extended wired board is the Magic Keyboard A1843, introduced in 2017. It has but one port, a Lighting port for charging it with the same cable that charges an iPhone or iPad:
